1. Field of the Invention
The invention relates to a technique involving the connection of solder balls (i.e. solder bumps) for electronic devices, and more particularly, to a redistribution connecting structure for solder balls.
2. Description of the Prior Art
In the conventional art, solder balls are commonly disposed on the output terminal of electronic devices for connecting to other external devices. As the demand for product miniaturization increases, the position of solder balls must be rearranged and adjusted accordingly. As shown in FIG. 1, a conventional redistribution connecting structure 100 includes a substrate 110, a first dielectric layer 120, a redistribution conductive layer 130, a second dielectric layer 140, and a plurality of solder balls 150. A plurality of bonding pads 111 is disposed on the substrate 110, in which only one bonding pad is illustrated in the figure. The first dielectric layer 120 is disposed on the substrate 110 and exposes the bonding pad 111 through a plurality of openings. The redistribution conductive layer 130 is disposed on the first dielectric layer 120. One end of the redistribution conductive layer 130 is processed to form a plurality of redistribution pads 131 for adjusting the position of the solder balls 150. The second dielectric layer 140 is disposed on the first dielectric layer 120 and the redistribution conductive layer 130. Preferably, the second dielectric layer 140 includes a plurality of circular openings 141 to proportionally expose a portion of the redistribution pads 131. The solder balls 150 are disposed on the redistribution pads 131. A plurality of ball bases 160 is disposed under the solder balls 150, in which the ball bases 160 are connected to the redistribution pads 131 through the openings 141, thereby establishing a connection for the solder balls 150.
However, when the solder balls 150 are disposed too close to the bonding pads 111 having no electrical connection thereof, a stress will result and break the connection of the solder balls 150 and cause the solder balls to peel off. If the size of the opening 141 is reduced directly, the bonding area and the adhesive ability of the redistribution pads 131 and the ball bases 160 will decrease accordingly and result in the same problem. Currently, the position of the solder balls 150, hence the position of the opening 141 of the second dielectric layer 140, is formed away from the bonding pads 111 having no electrical connection thereof. This design ultimately limits the redistribution effect of the solder balls 150.